1. Field of the Invention
The present invention relates to a current compensation module, a charging apparatus, and a charging apparatus controlling method thereof, particularly to a current compensation module, a charging apparatus, and a charging apparatus controlling method adopting a transition unit which is appended to the current compensation module in the charging apparatus application.
2. Description of the Related Art
Due to the impact of the greenhouse effect, employing clean energies have been gradually regarded in recent years. In order to alleviate greenhouse gas emissions, and then to supply the driving power to electric power equipment and electric vehicles, the rechargeable battery plays a critical role in the development of clean energies. Nowadays, the popular rechargeable batteries include Lead-Acid, Ni—Cd, Ni-MH, and Lithium ion (Li-ion) batteries, and these batteries can be found in various applications, such as powered forklifts, pallet trucks, and stacker. With regards to both energy and power density of a rechargeable battery, the lead-acid battery, the nickel cadmium battery, or the nickel hydrogen battery are all proven to be smaller than that of the Li-ion battery. Therefore, the Li-ion battery has become a better selection of a power source in the electric vehicle applications.
Compared to other rechargeable batteries, the Li-ion battery has the higher energy and power density and its application ranges have progressively extended from the portable electronic products to electric vehicles. However, due to the ever-increased capacious Li-ion battery should be implemented, the applied Li-ion battery pack has to be charged by a fast charger because it is hoped that the battery pack can be fully charged in a short time. Furthermore, a charging apparatus tends to provide either a constant voltage or a constant current to fulfill the purposed charging strategy for rechargeable batteries. Therefore, an inner circuit of the charging apparatus adopting a voltage compensative loop and a current compensative loop can be found in conventional art, so as to control the operations of the constant output voltage or constant current output to achieve the charging of the battery module.
Herein, please refer to FIG. 1A, which is the prior art of the inner controlling circuit for the charging apparatus.
The inner controlling circuit 90 of the charging apparatus in the prior art comprises a voltage compensator 91, a current compensator 92, and a PWM controller 93, wherein the voltage compensator 91 comprises an error amplifier A1 with the compensative components Z1 and Z2; the current compensator 92 comprises an error amplifier A2 with the compensative components Z3 and Z4. According to respective error-signals, which are from the output side of the voltage compensator 91 and the current compensator 92, the PWM controller 93 can be respectively controlled by a voltage compensator or a current compensator, and then the PWM controller can output the PWM signal P1 to control the charging apparatus. Before being operated in a constant-current (CC) output mode, as a charging apparatus is still in the start-up phase, its operations of the output voltage Vo, the output current Io, the inverting terminal voltage Vinv1 and the output terminal voltage Veai1 of the error amplifier A2 in the inner controlling circuit 90 of the charging apparatus are shown in FIG. 1B. FIG. 1B that is the prior art illustrates the waveform diagram of the output power and the control signals on the charging apparatus.
The inverting terminal voltage Vinv1 varies with the output current Io in direct proportion, and when Vinv1 is lower than the current reference command Vrefi, the error amplifier A2 is not operated in the feedback condition, and then the Veai1 will be sustained at a positive saturated voltage Vsat. With the ever-increased output current Io, when it exceeds over a maximum rated output current Io(max), the error amplifier A2 will be operated in feedback condition. As a result, the inverting terminal voltage Vinv1 can be clamped to equal the current reference command Vrefi. However, due to the output terminal voltage Veai1 which can not be rapidly clamped to the anticipative voltage Vant for the purpose of the constant-current output operation. For this reason, the charging apparatus will result and output an overshoot current Io(ost) during the delay time t1. Due to this overshoot current exceeds the specification of the rated output current, and it can damage the charging apparatus if this overshoot current is not suppressed.
In the “Current control type converter” of U.S. Pat. No. 7,830,683 ('683), the output voltage and current overshoot can be suppressed in the start-up phase of the power conversion apparatus is disclosed, in which the deviation detecting section is employed to detect an error value between the output voltage of the power apparatus and a reference voltage, and it can be used to determine whether the power conversion apparatus has achieved the start-up process. When the power conversion apparatus has completed its start-up process, the deviation detecting section outputs a signal, which calls the “completion of startup” to inform a control switchover section, then the compensator's operation on the control circuit of the power conversion apparatus will be switched from the proportional control mode to the proportional-integral control mode. As a result, the voltage or current output overshoot in the start-up phase of this apparatus can be suppressed. However, the system disclosed in U.S. Pat. No. 7,830,683 ('683) that needs to calculate the error value through the deviation detecting section to determinate the operative conditions for the power conversion apparatus. Then, a control switchover section receives a “completion of startup” signal from the deviation detecting section, so as to control to the compensators that its operations can be switched to a proportional calculation or a proportional-integral calculation. According to aforementioned methods, the drawbacks are revealed as follows:
First of all, it is complex that both the circuit structure and the control process; therefore, with regard to the research and development of productions is adverse. Second of all, the product cost cannot be effectively reduced because these controlling schemes and functions have to be realized depending on the bulky hardware circuits.
Therefore, in order to retrieve the drawbacks of the prior art, the applicants contemplate concerning the ameliorative innovation, to improve the aforementioned deficiencies and devise a current compensation module, a charging apparatus, and a charging apparatus controlling method to solve these absences of the prior art.